The night scene of the Squad shooting some bad guys & shoving them down a hillside, was shotin L.A.'s Griffith Park, along a stretch of the windingVista Del Valle.

Griffith Park is the largest urban park in the United States, containing over 4,300 acres.
It's part of the east end of the Santa Monica mountains. Much of it is rugged, natural
land of hills & canyons, but the park also contains the L.A. Zoo, the Greek Theatre,
the Observatory, Gene Autry Museum, golf courses,a merry go round,
Traveltown Railroad Museum, and the L.A. Equestrian Center.

The official address of the park is 4730 Crystal Springs Drive, but that will
only take you to the southeast corner of the park. These scenes were
shot on the winding roads in the hills west of the merry go round.
See the map links below for a more specific location:

Jerry & Grace are at a rustic-themed restaurant when a pair of Mickey Cohen's
men show up, and try to throw acid in Grace's face. Jerry stops them.

And yes, that elaborate redwood forest ambiance is real - Clifton's was (and is) something special.
Besides the redwood trees, the restaurant interior also features a waterfall, fake deer & bison, and a brook.
Built long before Disneyland, it's said that Walt Disney got a few of his ideas from Clifton's.

Clifton's opened at the height of the Great Depression, in 1935. Since then, it has served 170 million guests.The founder, Clifford Clinton, had a "Golden Rule" policy of letting people pay what they could afford.
Its once-popular Broadway neighborhood fell into disrepair in recent decades, but like the rest of
downtown L.A., Clifton's is making a comeback. It closed temporarily for renovation in 2011 and
should reopen soon - complete with a restored redwood forest.

[ A note of interest:Originally, the film featured a scene filmed at Grauman's Chinese Theatre,where gunmen fired through the movie screen into the audience. However, before the film
could open, something similar happened in real life, when a gunman opened fire at a
movie theatre in Aurora, Colorado. As a result of that tragedy, they postponed the
release date of "Gangster Squad", removed the Grauman's shootout scene,
and replaced it with this shootout filmed in Chinatown. ]

As the Squad assembles at night for their final assault on Cohen's gang,
we see a familiar sight behind them - the tower of Los Angeles City Hall.

Mickey Cohen and his gang are holed up inside a large hotel.
Cohen has rented out all the rooms, and turned the place into a veritable fortress.
It's here that the Gangster Squad mounts itsfinal assault on Cohen's forces,
resulting in a massive gunfight that begins on the front steps, moves in the lobby
(decorated for Christmas) and eventually spills out onto the street and into a nearby park.

In reality, this is the Park Plaza Hotel, at 607 S. Park View Street (at 6th Street),
two miles west of downtown L.A., overlooking MacArthur Park.

The spectacular building (its exterior complete with angels, towering columns and
Egyptian glyphs), was built in 1925 as an Elks lodge, and later became a luxury hotel.
(You can still see a bronze elk head atop the arching windows above the front entrance.)

The neighborhood deteriorated badly over the years, but the landmark building survived.
It is now used mainly as a filming location, and for special events such as weddings.

Both the interior and exterior of the building were used extensively in this shootout scene.

In the photo above, we're looking at the hotel's main entrance on Park View Street.
In the photo below, the scene is inside, shot in the hotel's lobby.